Rubber compositions containing guanidine compounds for applications other than vulcanization accelerators are conventionally known, including rubber compositions disclosed in Patent Literatures 1 to 3. Patent Literature 1 proposes a rubber composition containing: 100 parts by weight of a rubber component composed of at least one selected from the group consisting of natural rubbers and synthetic rubbers; and 0.05 to 20 parts by weight of at least one selected from compounds (A) having specific structures, for the purpose of providing a rubber composition having excellent heat aging resistance without reducing the rubber properties, and discloses a guanidine compound such as aminoguanidine as one of the compounds (A).
Further, Patent Literature 2 proposes a rubber composition containing a natural rubber and an aminoguanidine compound, for the purpose of providing a rubber composition containing a natural rubber having significantly reduced odors, while solving the problem of storage curing and achieving a stabilized viscosity over a long period of time, and also the purpose of providing a method for stabilizing the viscosity and reducing odors of the natural rubber.
Further, Patent Literature 3 proposes a production method involving compounding diphenylguanidine in the master batch-kneading step of kneading a rubber component, silica, and the silane coupling agent to improve the abrasion resistance while enhancing the reaction rate of silica with a silane coupling agent.